Messages in this thread | | | Date | Mon, 22 Jun 2009 09:32:47 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH] mm: pass mm to grab_swap_token |
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On Sun, 21 Jun 2009 14:02:43 +0100 (BST) Hugh Dickins <hugh.dickins@tiscali.co.uk> wrote:
> If a kthread happens to use get_user_pages() on an mm (as KSM does), > there's a chance that it will end up trying to read in a swap page, > then oops in grab_swap_token() because the kthread has no mm: GUP > passes down the right mm, so grab_swap_token() ought to be using it. > > We have not identified a stronger case than KSM's daemon (not yet > in mainline), but the issue must have come up before, since RHEL has > included a fix for this for years (though a different fix, they just > back out of grab_swap_token if current->mm is unset: which is what > we first proposed, but using the right mm here seems more correct). > > Reported-by: Izik Eidus <ieidus@redhat.com> > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> > Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> > Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
I already added my sign to Hannes but it is folded in this patch.
-- Kinds Regards Minchan Kim
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